Printers ejecting fluid from a fluid ejection nozzle array, such as ink jet printers, traditionally feature ink drops of the same size for a given color. The drop size or drop weight normally is chosen as a trade off between printing quality and printing speed. For achieving a high printing quality, such as one having a low drop visibility and small granularity of the printed image, small ink drops are desirable. This, however, goes at the expense of speed which asks for large ink volumes fired per unit time. High speed and through-put which can be achieved using large drop weights. Larger drops also create less aerodynamic effects, such as a distortion or deflection of the ink drop while it is travelling from the print head to the print media. Therefore, there is an apparent contradiction between image quality and printer throughput. One solution to this conflict is the addition of print cartridges including light inks which produce less grain visibility at a given drop weight.
While extra ink cartridges are a solution to the conflict of printing quality and printing speed, they are perceived as added costs and added complexity. Accordingly, dual drop weight print heads have been developed where a single integrated print head enables printing ink jet droplets of different drop weights. Such printers can fire any combination of small or large ink droplets on a given print position wherein the size and combinations of ink droplets are determined by the printer in order to provide an optimum printer quality and speed. Such dual-drop volume print heads eliminate the need for lighter inks, reduce image grain and increase the available color gamut for printing color images.
Further, printing systems are known which create different drop sizes or drop masses by controlling nozzles of the same nozzle geometry with different wave forms of a control voltage.
The present invention is applicable to printers having one or more fluid ejection nozzle arrays, such as ink jet printers, for example photo printers, small and large format technical printers, office and home printers etc.